It is known to use cationic surfactants in detergent compositions. For example, GB 2040990A describes granular detergent compositions comprising cationic surfactants.
Other detergent components often employed in detergent compositions are detersive enzymes which are known to assist in breakdown and removal of stains.
The Applicant has found that in some cases, particularly from some body soils, for example on collar and cuff stains, oily, greasy soils may contain proteinaceous soils which are difficult to break down because the greasy, oily soil component protects the proteinaceous component of the stain.
The Applicant has found that using a specific class of cationic surfactant in combination with a detersive enzyme, the greasy component of the stain is removed, exposing the previously protected stain and making it available for enzyme action. The combination provides improved cleaning benefits coupled with enhanced residual stain removal, the continued use of a detergent formulation according to the invention maintains good stain removal benefits prolonging the new look of washed garments.
Furthermore, generally, the stain removal performance of detersive enzymes is directly related to their concentration in the detergent composition, so that an increase in the amount of detersive enzyme increases the stain removal performance. It has however been observed that under stressed conditions, such as the use of short washing machine cycles, or at low temperatures or in the presence of highly stained substrates, the optimum performance of the detersive enzyme is limited beyond a certain level. Increasing the level of detersive enzyme beyond this amount does not result in increased stain removal performance benefits.
The Applicant has now found that these problems can be ameliorated by a detergent composition comprising a combination of a specific quaternary ammonium cationic surfactant and a detersive enzyme. The invention has been found to be particularly beneficial in detergent compositions which additionally comprise anionic surfactants.
Without wishing to be bound by theory, the Applicant believes that the particular cationic surfactants used in the detergent compositions of the present invention have surprisingly good solubility and form an association in the presence of anionic components to produce surprisingly soluble anionic/cationic complexes which lead to unexpected performance benefits. Furthermore, it is believed that following breakdown of the oily soil by the enzyme, the cationic surfactants used in the present invention may also form complexes with the fatty acids and any other negatively charged breakdown product produced, increasing their solubility and enhancing greasy, oily soil removal and overall cleaning performance.
All documents cited in the present description are incorporated herein by reference.